This Mississippi Mud Cake is a rich, homemade chocolate dessert topped with melted marshmallows and a warm, glossy chocolate frosting. It’s fudgy and dense—almost brownie-like—and perfect for chocoholics or anyone who loves a gooey, comforting treat.
Looking for an easy but impressive dessert? This cake is simple to make, forgiving for beginner bakers, and delivers deep chocolate flavor with melty marshmallow texture and a luscious chocolate frosting.
What is Mississippi Mud Cake?
Mississippi Mud Cake gets its name from the dense, gooey texture and the cracked, glossy surface of the chocolate topping that resembles the banks of the Mississippi River. Unlike a traditional airy sheet cake, this version is fudgy and indulgent, with chewy marshmallows layered on top and a river of warm chocolate icing that seeps into the cake.
If you enjoy the combination of chocolate and marshmallows, this cake will quickly become a favorite.
Reasons to Make Mississippi Mud Cake:
- Quick and easy to prepare—great when you want a decadent dessert without complicated steps.
- Rich chocolate flavor and gooey marshmallows make it the ultimate treat for chocoholics.
- Beginner-friendly: this recipe works with boxed cake mix, a bakery sheet cake, or a homemade chocolate batter baked in a 9×9 pan.
How to Make Mud Cake
You can use any chocolate cake that fits a 9×9 inch pan: a homemade batter, a simple box mix, or an unfrosted bakery cake. The key elements are the fudgy crumb, a full layer of marshmallows added while the cake is hot, and a warm chocolate frosting poured over them so it melts and creates that signature gooey top.
This decadent cake suits birthdays, potlucks, holidays, or any time you want a comforting, shareable dessert.
How do I store this cake?
Store the cake at room temperature for up to 4 days. Cover it tightly with plastic wrap or foil to keep it moist and prevent it from drying out.
Can I freeze leftovers?
Yes. The marshmallows may flatten slightly in the freezer but will regain some texture after thawing. Wrap the cake tightly in plastic wrap and a layer of foil to avoid freezer burn. Freeze for up to 3 months. Thaw in the refrigerator or at room temperature before serving.
Do I need to include the toppings?
Toppings are flexible. If you don’t like marshmallows, substitute chopped pecans or leave the cake with just the chocolate frosting—either way it will be delicious. The marshmallows add gooey contrast, but the warm frosting alone makes a rich, satisfying cake.
This dessert serves a crowd and is rich enough that smaller slices are perfectly satisfying. It’s ideal for special occasions or casual gatherings—every bite delivers a mix of textures and intense chocolate flavor. Enjoy!
- For the chocolate cake:
- 2 cups all-purpose flour
- 1 ½ cups granulated sugar
- ½ cup light brown sugar, packed
- ¾ cup unsweetened cocoa powder
- 2 teaspoons baking powder
- 1 ½ teaspoons baking soda
- Pinch of salt
- ¾ cup vegetable oil
- 2 eggs
- 1 teaspoon vanilla extract
- 6 tablespoons milk
- 1/3 cup sour cream
- 1 cup boiling water
- For the topping:
- 2 cups mini marshmallows
- ½ cup butter
- 6 tablespoons milk
- 3 tablespoons unsweetened cocoa powder
- 1 teaspoon vanilla extract
- 3 cups powdered sugar
- Preheat the oven to 350°F (175°C). Grease and flour a 9×9-inch baking dish and set aside.
- In a large bowl, whisk together the flour, granulated sugar, brown sugar, cocoa powder, baking powder, baking soda, and salt.
- Add the oil, eggs, vanilla, milk, and sour cream. Mix until combined, then reduce speed and carefully pour in the boiling water.
- Beat on high for 1 minute to aerate the batter slightly.
- Pour the batter into the prepared pan and bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.
- Remove the cake from the oven and immediately sprinkle the mini marshmallows evenly over the hot cake to cover the surface.
- Return the pan to the oven for 2–3 minutes, until the marshmallows are slightly puffed and beginning to melt.
- Remove from the oven and allow the cake to cool slightly before adding the frosting.
- Melt the butter in a small saucepan over medium-high heat.
- Whisk in the milk and cocoa powder and cook for 2–3 minutes, stirring constantly, until smooth and warm.
- Remove from heat and stir in the vanilla. Gradually whisk in the powdered sugar until smooth; use an electric mixer if needed for a silky texture.
- Drizzle the warm frosting immediately over the marshmallow-topped cake so it melts slightly and spreads evenly.
- Refrigerate the cake for about 30 minutes, or until the frosting is set, then slice and serve.
